Discrepancy found between empirical evidence and cannabis users' beliefs about medical marijuana

Researchers quizzed cannabis enthusiasts at a marijuana advocacy event about their beliefs on whether the drug is effective in treating certain medical conditions.

The majority of the nearly 500 people surveyed failed the quiz, according to the best science available.

"There is a big discrepancy between what the empirical evidence is saying and what people believe," said Daniel Kruger, PhD, the lead author of the study, which was published this month in the American Journal of Health Promotion.

"We've gone back to the 19th century miracle cure," added Kruger, a research associate professor of community health and health behavior in the University at Buffalo's School of Public Health and Health Professions and research investigator with the Population Studies Center at the University of Michigan.

"People are using cannabis and cannabinoids for everything and anything, and we don't have enough systematic research on whether it's effective for these conditions. People are stopping or reducing prescription drugs to use medical cannabis. It's a serious issue," he said.

And that's exactly why researchers felt it was important to survey marijuana users.

Researchers set up a table during Hash Bash, an annual marijuana advocacy event that has taken place on the campus of the University of Michigan for the past several decades.

The research team -- which included Jessica Kruger, PhD, a clinical assistant professor in UB's School of Public Health and Health Professions -- has conducted several previous studies with data collected at Hash Bash.

Among them was a paper published last spring that showed that the munchies exist, and that there's a need for tailored nutrition education as the population of marijuana users grows.

For the current study, nearly 500 Hash Bash participants completed surveys that asked about their cannabis use and where they obtained their information about marijuana.

They were also asked to respond to questions such as, "Which of the following conditions do you think marijuana is effective in treating (check all that apply)?" and "Which of the following conditions/events do you think marijuana use increases the risk for (check all that apply)?"

Participants' knowledge was compared with National Academies of Sciences, Engineering and Medicine (NASEM) conclusions regarding medical effectiveness and risk related to cannabis use.

In addition to revealing a disconnect between mainstream health and medicine and the medicinal use of marijuana, the study results also identified a lack of awareness of the potential risks involved.

For example, only 22% of respondents thought that cannabis use during pregnancy could be risky.

"That was really striking," Daniel Kruger said, adding that "there is evidence that marijuana use could lead to lower birth weights."

In addition, the majority of survey respondents said cannabis was effective in treating cancer, depressive symptoms and epilepsy. The NASEM assessment, however, concludes there is limited evidence that cannabis or cannabinoids effectively reduce depressive symptoms, and no or insufficient evidence that it works for cancer and epilepsy.

Participants also said marijuana can treat irritable bowel syndrome, despite, again, a lack of empirical data supporting that conclusion.

Kruger is quick to note the following caveat: Marijuana remains a Schedule I substance, which prohibits scientists from conducting the clinical trials necessary for properly informing NASEM conclusions.

The majority of study participants reported using marijuana every day, and 85% said they use it for health or medical reasons. About 78% said their knowledge of cannabis stemmed from personal experience, compared to just 23% from a medical cannabis caregiver or dispensary and 18% from a primary care provider.

The knowledge gap identified in the study is significant from a public health perspective, researchers say, adding that as a growing number of states legalize -- or consider legalizing -- adult recreational marijuana use, the conversation needs to shift.

These results highlight the disconnect between marijuana advocacy and policies and the lack of scientific evidence. We need more scientifically rigorous research to inform health messages that provide guidance about the use and effectiveness of cannabis and cannabinoids for a wide range of medical conditions."

R. Lorraine Collins, PhD, study co-author, associate dean for research in UB's School of Public Health and Health Professions and a contributor to the NASEM report

The issue is moving at a rapid pace due to citizen-driven ballot initiatives and pushes from public officials, Daniel Kruger added. For example, New York Governor Andrew M. Cuomo in his recent State of the State Address again called for legalizing marijuana for adult recreational use. Michigan voters passed a bill in 2018 approving legalizing, regulating and taxing marijuana there.

Given these efforts, it's time for public health to get up to speed, Daniel Kruger says. "Abstinence won't work as the only goal anymore. We need to maximize the benefits and minimize the costs, risks and harms to individuals and society. We hope our study broadens the conversation."